I use one to save a drill. One that was broken or chipped.

It puts a cone nose on the drill, not two flats. The back edge needs
relief.

I use cross point and never go small on drills - I do them by hand.
I use the 3/4" holder and standard holder - about 1/4 or 3/8 is the
smallest I'll go. Precision alignment must be done when setting up.

The cutting wheel is a diamond Ring. Do light cuts and don't get
it hot and burn the diamonds up.

Martin

On 9/9/2015 5:31 PM, Cydrome Leader wrote:
I grabbed a drill doctor 750X to play with. It sounds great in concept.

Here's my first thoughts from playing with it for an hour last night.

- construction is rather cheap, the quality of the plastic parts do seem
ok though, there' just too many of them. The thing wobbles around on the
table in the instruction video. The markings are crude and vague.
Everything it just a white dot. The parts are too complex for no reason.
I don't get it at all. The amount of knurles and holes and other crap on
the "dust cap" is mind blowing.

- the goofy looking cone device that holds the bit is just a chuck with
six sheet metal fingers for the jaws. It actually seems fine for the task.

- precision of the cam mechanism that lifts and rolls the drill bit across
the diamond drum is sloppy at best. It's just a bunch of plastic that
feels loose yet tight at the same time. It feels like there's plastic
springs in there, somewhere. The internal mechanism is some sort of cheap
die cast metal, but there's just too must plastic crap in the way for it
to be stable.

- the plastic door for cheaning out drill bit dust is a joke. It's like a
crappy remote control battery door that's too hard to operate and will
just snap off. It doesn't have to be made that way either. Cheap and fake
best describe that part.

Tried a 3/32" HSS bit at first. The thing leff jagged burrs all over the
cutting edge, had to stone those off after prying them up with my
fingernail. The bit works fine on wood, sort of struggles with aluminum.

The tried a bit around 1/16". Worked fine, no problems.

5/64th bit seemed ok, the cut surfaces still seemed too rough though, even
when cut with very gentle pressure.

Tried a cobalt bit that was also around 3/32" but had that weird high
speed spiral twist. Not sure what they're called. Tried to grind that to
132 degrees but the thing ended up completely flat like and endmill.
Something with the aggressive twist is messing up the "timing" of the
machine when you align the bit in the chuck. The video and PDF manual
mention nothing about how to deal with this sort of drill bit.

Next I tried the split point feature where you jam the bit into the side
of the machine and the side of the cutting drum cut into the bit at about
90 degrees. Since the fit of the plastic chuck and metal casting is tight
you have basically no control and it's all trial and error to even out the
flutes. What they show in the video is complete and utter nonsense.

The little machine really does cut bits rather quickly, but the cutting
drum is rather aggressive and the finish is really rough, even with a very
light touch. The cut surfaces are not smooth and really need to be stoned.

So far, it's a thumbs down. there's nothing the drill doctor can do other
than make a split point that I can't do by hand with my Tormek grinding
wheel. The Tormek can leave a mirror smooth finish if you want, and since
you can see and feel the cutting action you can control it quite
accurately, even by hand. Even if the angle you use is a little wrong and
both flutes match, you're golden.

I'll play with the thing some more to see what it does to larger bits and
to see if the thing runs better once the plastic starts to wear in some
more and the high points on the cutting drum get knocked off.

They seem to be a love or hate type of machine. Any other first hand
stories here with a drill doctor?